Not many studies have been performed comparing saw palmetto and a- adrenergic blocking agents, the other conventional drugs used in the treatment of BPH symptoms. In a small, double-blind study comparing saw palmetto with prazosin in 41 patients for three months, prazosin was found to have slightly greater effect on urine flow rate, nighttime urination, and amount of urine remaining in the bladder after voiding than saw palmetto. Studies comparing the effect of saw palmetto to that of surgery for symptoms of BPH have not been performed.

How does saw palmetto work?

The way in which saw palmetto works to relieve the urinary symptoms of BPH is unclear. Laboratory studies suggest that the extract of saw palmetto blocks the conversion of testosterone to its more active potent form, in the same way that the conventional drug finasteride does. However, studies in humans have not been able to confirm a significant reduction in activated testosterone. Other proposed mechanisms of action of saw palmetto include interference with the action of activated testosterone on prostate cells, as well as an anti-inflammatory effect.

What are the adverse effects of saw palmetto?

Adverse effects of saw palmetto are rare. They include headache, nausea, and upset stomach and are comparable in frequency to the symptoms experienced by the group taking the placebo. Erectile dysfunction has not been commonly reported among patients taking saw palmetto. It has been reported in 1.1% of men taking saw palmetto, 0.7% of men taking placebo, and 4.9% of men taking finasteride. The percent of men with erectile dysfunction after surgery for BPH is not clear. In one study, approximately 28% of men subjectively reported a decrease in the quality of erection after surgery; however, no worsening of objective parameters of erectile function were found. Although no drug interactions with saw palmetto have been systematically sought, no such interactions have been documented to date.

Is saw palmetto officially approved for use in BPH?

While saw palmetto is not officially approved in the United States for the treatment of urinary symptoms from BPH, it has been approved for this use in Germany. The German government assigned a commission in 1978 to oversee the efficacy and safety of herbal agents. The commission (German Commission E) reviews data from clinical trials and case reports, and considers opinions that they determine have merit.

What other concerns relate to using saw palmetto?

While the results of the trials are encouraging, the response from a product purchased from your local nutritional supplement store is not always predictable. This is because saw palmetto products are not standardized in terms of dosages or preparations. Even the available clinical studies used different doses and preparations of saw palmetto. The most common dose used in these studies was 160 mg twice per day. Since long term studies are not available, the incidence of adverse effects from the chronic use of saw palmetto extract has yet to be determined. Knowing adverse effects of the chronic use of saw palmetto is important because BPH is a chronic condition that requires continuous treatment indefinitely.

General information about saw palmetto

As a dietary supplement, saw palmetto cannot be claimed by its manufacturers to treat or prevent disease. Dietary supplements are regulated under the 1994 Dietary Supplement Health and Education Act, which does not demand particular testing procedures for the safety or effectiveness of these products before they are brought to market. Since they are not considered drugs under regulation by the Food and Drug Administration, prescriptions are not needed to obtain them in the United States.

What about the future of saw palmetto?

To establish the use of saw palmetto in the management of BPH, additional well designed studies are needed. Clinical trials must compare the efficacy and adverse effects of saw palmetto directly with those of the conventional medical and surgical treatments for BPH. We especially need data on the safety of ingesting this herb for the long term. Meanwhile, information should be obtained on what the active ingredient is in saw palmetto, and how it works in treating BPH.

Saw Palmetto At A Glance

• Saw palmetto is an herbal treatment for symptoms of benign prostatic hypertrophy (BPH) such as hesitancy, urgency, dribbling, increased frequency in urinating, and increased nighttime urination.
• Saw palmetto is comparable in effectiveness to conventional medication in the treatment of urinary symptoms associated with BPH.
• Short term use of saw palmetto has fewer adverse effects than conventional medications for BPH.
• The incidence of adverse effects from long term use of saw palmetto is unknown, and long term treatment is needed for BPH.

Reference: FDA Prescribing Information

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